Add a new Sight trait, implemented by PlacedPiece. The implementation of this
trait produces a BitBoard representing the squares visible to the placed piece.
- ASCIIDisplay → format a type using ASCII only characters
- UnicodeDisplay → format a type using any Unicode characters
- FENDisplay → format a type for inclusion in a FEN string
This macro implements a tiny DSL for creating Pieces and PlacedPieces.
"White King" → Piece::new(Color::White, Shape::King)
"White King on E4" → PlacedPiece::new(Piece::new(Color::White, Shape::King), Square::E4)
Move position.rs to the position module and create a mod.rs.
Do the same for bitboard.rs in the bitboard modules.
Export Color, Piece, Position, and Square and use crate::Thing directly instead of referring to the symbol in the nested modules.
